More infection needed for protection? The good vs evil in malaria. Your Photo More infection needed for protection? The good vs evil in malaria. Priyanka Barua, PhD, Year 3, Department of Medicine, The University of Melbourne. Introduction Do you need more infection by malaria to become protected from it? If you are from any country that is not currently affected by malaria, then beware! Because when you are travelling to a country where there is malaria, you can get infected by a single bite of an Anopheles mosquito! Surprisingly, people from areas having ongoing malarial infection are somehow protected from getting malaria to some extent.1 Results Children who had malarial infection between 6 to 18 months of age had higher level of antibodies (proteins used by the immune system of the body to identify and fight against harmful organisms) to certain antigens than the children without any malaria. Image: An Anopheles mosquito (a mosquito known to transmit the malarial parasite) feeding on human blood.2 Approach Blood samples were tested from 432 children in their 6 and 18 months of age from Malawi; a country where malaria occurs frequently. The method of testing was called ELISA or Enzyme linked immuno-sorbent assay which is used for detecting the presence of foreign substances (antigens) in the body. Conclusion Having protective antibodies after being exposed to malaria actually prevents the person from getting severe infection later. So malarial infection in early age can be one of the ways to get protected from severe malaria. However, these antibodies are very short-lived and repeated infection is necessary for boosting it.3 Figure: Antibody levels were higher in those children infected by malaria (showed symptoms and tested positive for malaria) than children without malaria.

References Acknowledgements Doolan, D. et al. (2009). Acquired immunity to malaria. Clin Microbiol Rev. 2009 Jan; 22(1):13-36. Jim Gathany, Anopheles stephensi, Content Provider: CDC [Public domain], via Wikimedia Commons https://commons.wikimedia.org/wiki/File:Anopheles_stephensi.jpeg#/media/File:Anopheles_stephensi.jpeg Gupta, S. et al. (1999). Immunity to non-cerebral severe malaria is acquired after one or two infections. Nature Medicine  5, 340 – 343. Acknowledgements Dr Stephen Rogerson, Professor, Department of Medicine (Royal Melbourne Hospital), The University of Melbourne. Dr James Beeson, Head of Centre for Biomedical Research, Burnet Institute.